Generating Cash Flow from Toll Milling and Small Scale Mining

ENVIRONMENTAL AND SOCIAL BENEFITS
Toll milling has a direct environmental and social benefit to the people of the region as it
eliminates the use of mercury and its health effects while increasing the amount of money
the artisanal miner makes by increasing his net yield.
• The artisanal gold mining sector in Colombia has 200,000 miners officially producing
30 tonnes Au/a.
• Miners crush and amalgamate the whole ore, without previous concentration, and
later burn gold amalgam without any filtering or condensing system, often in the
same building that the family lives in.
• A percentage of the mercury added to small ball mills (cocos) is lost: mostly with
tailings (typically dumped in rivers) and some when amalgam is burned.
• Air mercury levels range from 300 ng Hg/m 3 (background) to 1 million ng
Hg/m 3 (inside gold shops) with 10,000 ng Hg/m 3 being common in residential areas.
• The WHO limit for public exposure is 1,000 ng/m 3 . The total mercury
release/emissions to the Colombian environment can be as high as 150 tonnes/a
giving the country the first position as the world's largest mercury polluter per
capita*
* Global Mercury Project in Colombia for the United Nations.
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